I am very much outdated, but I have just upgraded my project to use JDK 1.5 from JDK 1.4, and now when running mvn javadoc:javadoc, I encounter the following javadoc warnings:
[WARNING] javadoc: warning - Multiple sources of package comments found for package "com.a"
[WARNING] javadoc: warning - Multiple sources of package comments found for package "com.b"
[WARNING] javadoc: warning - Multiple sources of package comments found for package "com.c"
[WARNING] javadoc: warning - Multiple sources of package comments found for package "com.a"
What do I need to do to fix them? Has anything changed from JDK 1.4 to 1.5?
Thanks!
(Updated 10 years after the original answer.)
An old thread in the Oracle forums discussed this. (Unfortunately the link is broken now, and I can't find the same thread in the new Oracle Developer community, nor in the Wayback machine).
As far as I recall (and could gather from a bit of google-ing), the behavior of javadoc changed between JDK 1.4 and 1.5 so that a package documentation encountered multiple times creates this warning. This seems to have happened specifically with older versions of Maven – updating to a newer version of Maven (or the maven-javadoc-plugin) seems to have helped.
(Of course, that meant a Maven version which was current in 2011, so any version you might have nowadays should be fine.)